Fat Loss & Fast Metabolism with Intermittent Fasting? Not So Fast

If you’ve been even remotely involved in the nutrition or fitness community over the past few years, you at least know the term intermittent fasting (IF). Enthusiasts praise its pattern of orchestrated eating and abstaining for everything from improved immunity to mental clarity and, of course, fast fat loss.

IF involves periods of alternately eating and fasting. Beyond that, definitions widely vary. Some people do IF for hours each day, while others fast for 24 – 36 hours once or twice a week. Eating could involve anything from a low-carb diet to carb loading. Fasting might be nothing but water, or supplementing with branched-chain amino acids (BCAAs) and protein powder. Many people use green tea and fiber to curb appetite and cravings while they do IF.

A Google search will reveal the numerous methods of IF, most written by bloggers and fitness professionals emphatically singing its praises for fat loss, increased stamina and vigor, improved focus at the gym and at work, and breaking plateaus.

From all that information, you’ll likely conclude that IF is the “miracle” for becoming your leanest, healthiest self. But is it? I want to take a more objective look at some of its often-overlooked pros and cons. As I’ll discuss, I’m particularly concerned that IF could lead to food intolerances, binge eating, and most troubling, eating disorders.

Pros of Intermittent Fasting

You might get fast fat loss. Most studies showing IF can improve fat loss also look at caloric restriction. One study, for instance, found IF combined with calorie restriction and liquid meals helped obese women lose more fat and improve their cardiovascular disease risk. Obviously, when you restrict food to a certain time period, you will usually (but not always) take in fewer calories.

You give your digestive system a break. Between constant snacking and meals, your digestive system becomes compromised, leading to leaky gut and other gut-related problems. IF gives your overworked digestive system a much-needed rest for recovery and repair.

Longer periods without eating let your body reach into its fat stores. I’m opposed to snacking because every time you eat, you elevate your insulin levels and potentially store fat. Conversely, restricting food to a certain time period during IF reduces how often you raise insulin levels, therefore encouraging your fat cells to release fat for fuel.

A different relationship with food. We are a nation that constantly eats, beginning with a low-fat muffin (aka dessert) with our morning dark roast to that spoonful of Ben & Jerrys before bedtime. IF allows you to stand back and observe your relationship with food. When you no longer gravitate to comfort foods, for instance, you may need to confront emotional eating and determine what leads you to do that so often. We are also afraid of being hungry, and really being with that feeling when you do IF can create a new mental and even spiritual clarity about your relationship with eating. In other words, IF can reveal some deeper truths about yourself that you might be avoiding by self-medicating with food. And though they may initially be painful, doing so can greatly benefit you in the long run.

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Cons of Intermittent Fasting

IF could lead to eating disorders. The binge-and-purge mentality of IF could trigger or exacerbate bulimia and other eating disorders at its most extreme. The “anything goes” mentality some experts permit during the feeding state could lead someone to overeat, leading to guilt, shame, and other problems that only become worse over time. I’m not saying this happens often, only that it could happen if someone already has emotional eating or other problems.

IF might do more harm than good for women.Studies show that for women, alternate-day fasting could actually lower glucose tolerance and potentially crash your metabolism. Other research shows IF can trigger sleeplessness, anxiety, irregular periods, and hormonal dysregulation for women. Stress, which I’ll discuss below, can only exacerbate those problems. Especially if you’re female, consider these factors before you try IF.

Elevated cortisol levels. Skipping meals raises your stress hormone cortisol. Among its duties, elevated cortisol stores fat and breaks down muscle. I’ve known people who did IF and actually gained weight. One reason is cortisol.

An obsession with food. I discussed earlier how IF could create a deeper, self-revealing connection with food. The flipside is that you might constantly focus on food. See, hunger is a powerful evolutionary mechanism that kept us alive back in the day. With our modern ubiquitous bodegas and snack machines, hunger isn’t normally a problem and we rarely confront it. The problem is when you’re starving everything else takes a backseat to eating. With IF, that could become an obsession with mentally planning your next meal. In other words, everything becomes about food.

Over-reliance on coffee. Most IF plans allow caffeine, which is a stimulant that can keep you going for hours when you’re not eating. If you’re a coffee drinker doing IF, you might find yourself gravitating to Starbucks more often to get your fix that keeps you going without food. Coffee also exacerbates your already-high cortisol levels, making fat burning more difficult and potentially breaking down muscle.

A tendency to overeat. Even if you’ve never done IF, you know the feeling of missing lunch and then devouring second or even third helpings at dinner. That caloric-restriction benefit I mentioned earlier disappears if your next meal becomes a free-for-all, especially if those calories come in the form of deep-dish pizza and a hot-fudge sundae.

Potentially increased food intolerances. Free-range chicken and organic broccoli might be your go-to “break the fast” meal, but then you might mentally permit yourself to nosedive into a double cheeseburger as a “reward” for fasting. Hunger, after all, can override any sense of logic or disciplines. Several IF experts I’ve encountered encourage a “free for all” during your eating hours, which can become a food-intolerance nightmare that sets the stage for blood sugar spikes and crashes, cravings, leaky gut, increased inflammation, and many of the other problems I discuss in The Virgin Diet.

My Take

Done correctly, IF could provide some benefits if you’ve hit a fat-loss plateau or want to deviate your routine. As a quick fix for fast fat loss, I believe it’s less effective, and potentially could do more harm than good. In its worst case, IF done incorrectly or fasting for too long without supervision could lead to permanent damage to your metabolism and your health as well as the aforementioned eating disorders.

That aside, if curiosity or wanting to get into your swimsuit by summer prompts you to try IF, I have a few suggestions.

Downsize the caffeine. Keep it to one cup of coffee and then switch to green tea, which has fat-burning EGCG and calming theanine.

Plan your meals ahead of time so you don’t obsess over what you’ll eat or overeat at your “breaking the fast” meal.

Remember that hungry as you might be, breaking your fast does not mean engulfing large amounts of food, which is a quick way to undo your efforts.

Try a scoop of Extra Fiber with water every hour or two during your fast to stave off hunger.

Yoga, deep breathing, or meditation can help reduce cortisol levels.

Branched-chain amino acids (BCAAs) every few hours when you fast can help curb appetite and cravings as well as reduce cortisol levels.

For more modified version of IF, do The Virgin Diet All-in-One Shake for 2 meals a day and then The Virgin Diet Plate for dinner. You’ll still get most of the benefits of IF without the discomfort.

IF Without the Hunger? Try This Approach

Maybe you want to put your foot in the IF pool without fasting most of the day or even several days. Here are 2 more sane ways to try it.

One is to skip dinner 2 nights a week. You’ll do a substantial breakfast and lunch, giving you an impressive 18 – 20 hour fasting window. Employ my tactics above to curb hunger.

If you don’t want to skip meals, the other way is even easier. One recent study found that mice restricted to eating only 8 hours a day lost more fat and improved their health better than mice that grazed whenever they wanted, even though both groups ate the same diet.

Likewise, you can get most of IF’s benefits by fasting 12 – 14 hours a day. Enjoy a healthy, substantial dinner at, say, 6 p.m. and then close up the kitchen for the night. Have a protein-rich breakfast at 8 a.m. the next morning, and you’ll get about a 13-hour fasting window.

Since you’ll (hopefully!) be sleeping most of those fasting hours, you’ll have little or none of the deprivation, hunger, and other miseries that come with more extended fasts but all of IF’s benefits. To me, that’s the best of both worlds for fat loss, fast metabolism, and optimal health.